becker



J. BECKER.

FOCUSING CAMERA.

APPLICATION FILED SEPT. 24, I918.

Patented June 24, 1919.

I! SHEETS-SHEET 2- .I. BECKER.

FOCUSING CAMERA.

APPLICATION FILED SEPT-24,1918.

Patented June 24, 1919.

I I SHEETS-SHEET 3.

vktwkww ienq UMW e M m 2 9 9 x Nx ..x.! x N @ifi 3 NNQ u M w I J. BECKER.

-FOCUS!NG CAMERA.

APPLICATION FILED SEPT- 24. 1918.

1,307,339. Patented June 24, 1919.

II SHEETSSHEET 4.

Invefzor J. BECKER.

FOCUSING CAMERA. APPLICATION FILED SEPT- 24, I918.

Patented June 24, 1919.

I I SHEETS-SHEET 5.

g 6| F\ Y 6.2" 62 J. BECKER.

FOCUSING CAMERA.

APPLiCATION FILED SEPT- 24, 1918 1,307,339. Patented June 24, 1919.

l I SHEETS-SHEET 9- NN'=+S cm Vector ZD B I 7.0 cm

FF 65 cm. Vector Z'D' b 45' cm.

ZK K"K' KZ' FF Bx L fx f 8 3 13 65 cm 10x45 30 x 30 900 Co-basic Angle ga.mma. 66 5 0.738 Q Basic Anglia dQltO H3035 Q E? Effective Base line m: k V336 4V2 3.33 cm ffective baseline D'K' k V|7o| 9V?! 44.7.4. cm.

f M-M UNITED STATES PATENT OFFICE.

JOSEPH BECKER, OF WASHINGTON, DISTRICT OF COLUMBIA, ASS IG-NOR TO EASTMAN KODAK COIEPANY, OF ROCHESTER, NEW YORK, A CORPORATIQN OF NEW YORK.

FOCUSING-CAMERA.

Specification of Letters Patent. Patented J 11119 2-}, 1919.

Original application filed August 11, 1900, Serial No. 26,647. Divided and application filed April 3, 1916, Serial No. 88,619. This continuation application filed September 24, .1918. Serial No. 255,491.

To all whom it may concern:

Be it known that I, J osnPH BECKER, a citizen of the United States, residing at Washington, in the District of Columbia, have invented a certain new and useful Improvement in FocusingCameras, of which the following is a specification.

The present patent application, identified for convenience ofreference as Case Be, continuing Ai or Division Two of A, is a continuation of my allowed, herein merged, and therefore hereby abandoned prior applicationCase Ai, Serial No. 88,619, which was itself filed April 3,. 1916, as original Division Two of my still earlier Case A,

I Serial No. 26,617, filed August 11, 1900, and

now Patent 1916. Y

My present Case Bo, and my hereinafter specifically referred to related applications or patents, may all be listed in their filing No. 1,178,171, issued April 1,

date or letter name order, as follows: My

just mentioned parent case, Case A, now Patent 1,178,171, issued April'1, 1916; Case B, now Patent 1,178,175, issued April 1. 1916; Case 1, Serial No. 211,152, filed June 7, 1901, now abandoned but revived partly as Case Af and partly as Case Aj; Case K, now Patent 1,103,312, issued July 11, 1911; Case 0, now Patent 1,103,313, issued July 11, 1911; Case T, now Patent 1,112,295, is sued June 8, 1915; Case U, now Patent 1,199,211, issued July 1, 1916; Case X, Serial No. 727,518, filed December 21, 1912, abandoned but now reprosecuted as Case 'Bd; British Patent 29,701, filedDecember 21, 1912; Case Y, Serial No. 732,188,. filed November 20, 1912, now merged in-and continued as Case Au; Case Ab, now Patent 1,178,177, issued April 1, 1916; Case Ae,

Serial No. 66,371, filed Dec. 11, 1915; Casey Af. (based on and amplifying a revived art of my said abandoned Case I) now atent 1,178,178, issued April 1, 1916; the herein merged Case Ai, Serial No. 88,619, filed April 3, 1916, as original Division Two of my said Case A, and allowed April 5, 1918; Case Aj (based on and amplifying a second revived part of my saidzabandoned Case I) Serial No. 88,719, filed April 3, 1916; Case At, Serial No. 113,085, filed January 18, 1917; Case A=u, or continuation of my said Case Y, now Patent 1,280,368, issued October 8, 1918; Case AX or Division 3 of A, now Patent 1,210,788, issued Sep tember 18, 1917; my present Case Bc, Serial No. 255,191, filed September 21. 1918; my later Case Bd, Serial No. 258,167, filed October 16, 1918.

My said parent Case A, inFigures 1 to 21, discloses what, I have since called, in my said Case Ae, theoretically exact focusers of the radial cam type; but ins-aid Case A (page 3, lines 51 to 63) I expressly refrained from making any claim to such devices, because I had not yet discovered the hereinafter disclosed positive method of ad iusting mirror N in Fig. 19 of said Case. A, which adjustment is now to be used in place of the tedious tentative adjustment described in lines 5 to 20 on page 11 of the said Case A, and preferably so as to constitute adjustment number one in a series of three entirely independent special 7 adjustments that are used substantially as already described in each of my said prior Cases'K, O, T, U, Y, Ab, Ae, Af, At, An, to secure exact 3-and-hence-all-pointcorrespondence 7 between the focuser and any one of-difierentlenses, without knowing the, focal length of the particular lens used, or any other one of its characteristi features. I c

The present invention therefore consists in the theoreticallyaccurate radial cam optical focusers disclosed in Figs. 1 to 21 of my said Case A; and the focuser of Fig. 19, Case A, with its hereinafter disclosed simpler equivalents, being the most .complete, is selected as representative of all for present purposes. v V

In the accompanying drawings Fig. 1, substantially identical with Fig. 19 of my said Case A, is .a side view of a camera having its focuser parts fully ad- I Fig. 2 is a detail .view showing the special mount of the fixed mirror Nas it is seen looking downwardly in the direction of the slightly inclined arrow 36, ig. 1. c

45 1 made' on right-hand infinityg-and which Fig. 3 is a side view of the special mount 7 used in my said Case A for pin J of Fig.

1; but which is now preferably discarded for. the mechanically complete form of great distance or infinity; (2) for a second mount shownin the present Figs. 12 to 15.

Fig. 4, distorted forclearness, illustrates the tedious, tentative, and herein preferably discarded method of adjustment which was used. in my said Case -A, to secure exact correspondence between the mirrors and the camera lens for (1) an object point 0 at a object point 0" at close range; and (3) for a third intermediate object point 0"; such 3-point correspondence, once obtained in a theoretically exact focuser like the present,

being suflicient to secure all-point correspondence, as already explained in my. said Case A, more fully in my said Case Ae, and in my said other Cases K, O, T, U, Y, -Ab, Af, Ai, At, An; that is to say, as fully ex- 1 plained in all of my above-enumerated cases after excepting Case B and Case Ax, which only make slight references to a theoretically exact form of focuser. i

.Fig. -5 is a scale of parts in Fig. 1, one hundred parts long, with each part (abbre-,

viated as ufor unit) representing about 3 a 7 ,millimeters inthe finished structure, but a1)- 0.

'- tol-board application drawings, as one millipearing, on the original 10-by-15 inch br1smeter; and,- therefore, all dimensions hereingiven, after allowing for variations produced by dampness in paper,'may easily be verified with this Fig. 5 scale and-with a metric rule, not only on the present drawings, but in Fig. 1 of niy said herein merged Case Ai, and on the original Fig. '19 of my said Case A, both of which are kept accessi'ble to the public, in-the archives of the Patent ()fiice,

Fig. 6 is a; semi-diagrammatic representation of the Fig. 1 camera as it a pears immediately after completion of t e present new adjustment number A one which is serves to locate the normally "stationary mirror in its proper position N, quickly, posi" tiyely, and branch manner that its position will not requlre anysubsequent alteration.

Fig. 7 is a semi-diagrammaticrepresentation of the Fig. 1 camera as it appears immediately after completion of the present new adjustment number two, which is made on left-hand infinity as already described in my aid Case A, and which serves to determine te rectilinear locus of the image frame pintle J.

' and p, and which serves to determine, on

locus 40 of Fig.7, the exact position V of pintle J i a Fig. 10 is a scale for. Fig. 9, similar to the u unit scales of Figs. 5 and 8.

Fig. 11 is a, table of the fundamental dimensions-in the present Fig. 1 camera, and therefore also in the Fig. 19, Case A, cam

era; all values that are given in the table being the result, either direct or calculated,

of measurementsmade with a metric rule on the previously referred to' original 10-by-15 inch bristol-board drawing of my said Case A, whose fundamental dimensions were drawn in exact proportion, hence also angletrue, though not to any stated scale, the black quadrant means: for lens F.

Fig. 12, on a scale twice as large as that of- Fig. 1, .is a side'view of my present preferred and mechanically complete formv of mount for pintle J, to be used in place of the mount shown in the presentFig. 3, or in place of that shown in Fig. 21 of my said Case A, with the object of avoiding all marks, such as line 40 seen in'present Figs.

7 and 9, or line 50 seen in present Fig. 9, so 'that'all adjustments shall be mechanically complete in every particular. Fig. 13 is a rear end elevation of the same after insertion of the two bolts 146', 147.

Fig. L1 is a side view, corresponding to Fig. 7, showing how the said mount of Figs.

12 and 13, is automatically set during adjustment number two, at its proper height and inclination on frame 12, that is to say,

in proper osition for clamping.

Fig. 15, on a scale twice as large as that of Figs. 12 to 14, is a sectional view taken on plane 15 of Fig. 14 looking in the direction ofarrow 15.

Figs. 16, 17, 18, 19, 20, and 21, corresponding respectively to Figs. 6, '7, 8, 9, 10, and 11,

show a simplified form of optical focuser which is derived from the Fig. 1 type, without changing any of the fundamental dimensions, simply by substituting a direct radial sightingarm AB in place of, and rotating twice-as fast as the lower pivoted mirror M.

Mirror N is retained to serve as a peep in combination with the image 'A of pin A acting as a bead to determine the direct horizontal sight'line NAG.

Figs ;'22, 23, 24, 25, 26 and 27, also corresponding respectively to Figs. 6, 7 8,:9, 10 i and 11, show a still simpler form. in which (1) the'two, radial arms AR, AR of 16, 17. and 19 are mounted on. the same pivot A, so that they may be rigidly connected;

and (2) the upper mirror of the same Figs.

16, 17, 19, is replaced by a plain, vertically adjustable but constantly horizontal sight,- ing arm-406. 7 f

Fig.28, corresponding to Fig.3 of my said Cases K and 0, also to Fig. 50f my said Case T, and especially to Figs. 6 and 8 of my said Case U,-is a semi-diagrammatic reprenals V i and V directly and respectively mounted in the two structurally represented conjugate planes P and-P of the lens 500.

Fig. 29 represents, at the same scale as F ig. '28, a centimeter scale which is to be used in measuring all the fundamental linear dimensions of Fig. 28.

Fig. 30 is a table of the fundamental linear and of the fundamental angular dimensions in Fig. 28.

.Fig. 31 shows the camera of Fig. 28 as it would appear if its left conjugate plane P could beshifted all the way toleft infinity.

Fig. 32 shows the same camera of Fig. 28 as; it would appear if its right-hand conjugate plane P could be shifted all the way to right-hand infinity. v

Fig. 33 represents a centimeter scale to be used in measuring all fundamental linear dimensions in Figs. 31 and 32-. 7

Fig. 34 shows a more general form of mechanical-focuser, derived .from that of Fig. 28. without changing any of the fundamental dimensions, by simply translating the left-hand section of the focusing gear in Fig. 28, horizontally to the right, through a distance of nine centimeters; such shift being structurally represented by the ninecentimeter bar 172, the nine-centimeter bar w, and a'new link 609, shorter than link 509 ofFig. 28.-

Fig. 35 is a two-sight optical focuser of the same type as that seen in Fig. 19. but/derived from the,.meclianical"focuser of Fig. 3f by simply invertingthestructure of said Fig.

34:, without. changing any of its dimensions,

but after having substituted a sighting arm or alidade DR for the mechanical radial cam DR.

Fig. 36 represents a centimeter scale to be used in measuring the fundamental linear dimensions in Figs. 34 and 35, such dimensions being the same as those listed in Fig.

30 for Fig. 28; excepting that K K is 'now 30 instead of 39 cm.

The principal novel features of my present.- invention are: first, that the properly adjusted device, in all forms herein shown or referred i to, is theoretically exact for all object distances, and is nevertheless capable of an infinlte number of variat ons, 1n arrangement and proportion, either with or without mirrors,

to suit the special requirements of any given case, because the pivots Aand A may each be located independently, in any arbitrarily preferred positions on the lens frame of the camera; secondly, that the novel, quick,.posi tive, and accurate method of adjustment herein disclosed does not necessarily involve any change whatever in the structure or pro portionsof the Fig. 19, Case A, camera as first disclosed in 1900, although in the pre ferred form it does involve the slight change in structure seen in'Figs. 12 to 15; thirdly, that the device has special features which permit of either folding the camera for transportation or of opening it up for use,

without paying any attention to the mechanical connections in the focuser, as such connections are adapted to recover their camera is opened up for use.

. Camera of Figs. 1 to 5.

The camera of Figs. 1 to 5 is identically the same as that of Figs. 19 to 22 of my said Case A, and it will be described in substantially the same terms, both structurally and in its adjustments, so that there shall be no doubt whatever that the present additional disclosures are simply complementary, and do not involve the slightest departure in principle.

The camera proper comprises an upright rigid frame 10 which supports a camera lens F, whose four cardinal planes pass through the points F F F F.,; or which supports, in place of lens F", any otherlens, such as the diagrammatically represented lens E, whose four cardinal planes would pass through the differently spaced set of cardinal points E E E E The lens frame 10 has a horizontal extension 13 hinged at 13', for folding, but normally adapted to form a slideway for a block that supports the movable image frame 12. A bellows 11 is used to establish an extensible light proof connection between the stationary lens frame 10 and the movable image frame 12.

The focuser comprises a -metallic base plate 34, 35, 36, fastened to the lens frame 10 bythree screws 34', 35', 36. The upper part 34 of this base plate is formed as a dovetail rail, Fig. 2, to serve as a guide for a small carriage 33 which supports the normally stationary eye mirror or peep N.

This mirror N may be fixed at any desired elevation on rail 34 by tightening the clamp screw 37. Fig. 1 shows it in two positions distinguished as (1) position N which would be correct for the unmounted lens E"; and (2) position i 1 which is correct for the mounted lens F.

The dovetail rail element 34 of the focuser base should preferably be parallel to the upright 10, but it is here shown alittle inclined to emphasize the fact that it does not have to be upright to secure correct operation. Mirror N, however, must be fixed at the proper inclination to bisect the angle that the rail 34 forms with the horizontal line of sight ENA.

The lower. expanded part 35,36, of the focuser base plate has a pivot or pivot bear ing A for a pivoted mirror M, whose rigidly equal angles A and t, or minus twice the acute angle at A. The angular motions of .arm A't'or 51 must therefore be exactly twice as large as those of the mirror arm 4:9; that is to say, twice as large as the an gular motions of the mirror M. A more detailed proof of this proposition is givena in lines 59 to 83, pagej6, and Figsmi and 5 of my said Case A, where all possible '20 F and F determining a focal length F,F Y

variations in the position of a similar pintle p, on an arm D, are fully discussed.

Am 51 has a slot R which is mainly radial, to serve as a radial cam, for focusing, but which is bent'as shown at its lower,

and not otherwise used, end to insure that the arm 51 shall automatically, assume the proper upright or folded-up. position,"

shown m dotted lines, when the nnage frame 12 has been brought up againstthe lens frame 10 in folding the camera.

The radial slot R of arm 51 engages a pin J'- which is adjustably mounted on theimage frame 12,- as shown in Fig. 3, where pin J is seen to be fixed on a carriage 38. This carriage has a clamp screw 38'- for clamping it in any desired longitudinalposition on the guide rail 39, which is itself fastenedto the image frame by means of two screws 39' and 39".

The ends of the guide rail 39 are nicked centrally at 41 and 41' to assist in properly locating the guide rail 39, with reference to the mark 40, which is traced on the image frame 12 in the process ofad'justment described farther o The 'focuser is shown regulated'and ad-' justed for use with. the mounted lens F which has its four cardinal points at F F F F The principal foci are at .F

and F ,'while the two nodal points are at or F F or f equal to unitsof Fig. 5.

In accordance with the principles set forth in Fig. v23 of my said Case A (where the the scale in general arrangement is the. same as it is here, but turned upside down), thedirect 1 Horizontal sight line through the center of the eye mirror N meets the-outside focal plane F, of the lens F in G which determines the length and inclination of the main basic inclined vector AG of the focuser, and therefore, also the basic focuser angle r at G, This basic focuser angle 1' at. G is the 1,ao'i,sae I a A same as the angle 1' at G in Figs. 18 and 23of my said Case A, and is now identlfiedm my said later Cases Ae, At, and Au, also in my present more complete diagram Fig. 35, as the angle epsilon prime (e') at Z. Hence G is identified as point G(Z).

- All other. parenthetically inclosed reference signs of the present Fig. 1, are similarly reproduced from the present Fig. 35, p

and, in the latter, from my said other Cases Ae, At, Au.

With the parts in focus on infinity, as shown in Fig. 1, the pivoted mirror M is parallel to the eye mirror N,- and the indirect broken or reflected ray WA, AN, N'E, or R, 61', 62', coming horizontally from infinity, traverses the outer focal lane in W, determining a'rectangular triangle .WAG, .whose angle eta prime (n')- is evidently equal to the acute angle zeta prime (C), which is itself supplementary the basic obtuse angle 2 of the focuser.

It is evident, in Fig. 1, that p '=sin 1 :WG/AG "(1') also that the basic angler: (180 AG is? 91 mm.; exactly as reproduced in the l0-by-15 inch bri stol-board drawing of the presentFig. I; andthese two measurements are suflicient to-determine: first, by equation 1 the sine of angle zeta prime (C') ;-secondly, with a suitable ta'ble, angle Now, in the original 10-by-15 inch bristolboarddrawing, Fig. 19 of my said Case A,

the distance WG is 49 mm; and the distance zeta'prime itself; and thirdly, with equa- ,tion 2, the supplementary angle 1', vwhich is the basic angle of thefocuser. That is to say:

x where Q, stands for the quadrant or one right 7 angle As terminal J, in'F'ig. 1 occupies its extreme left-handor zero position, its axis coincides with the stationary point H, which 1s 1dent1cal with point H of Fig. 23m my said Case A, also with ent Fig. 35.

The vector A'H, therefore, is the secondpoint of my presary base line of the focuser, whichmust satisfy two conditions, to 'wit: first, its

inclination, eta (1;), must be equal to the inclination eta prime (-9) of the oppositely inclined, and therefore anti-parallel main base line AG; secondly, its length, A'H, must be such that the product AG.A'H of these two anti-parallel focuser base lines, AG, A'H,

shall be equal to the square of the focal length; or, in the symbols of my said Case A Angle-1' at H angle 1' at .G- (3) For the mounted lens F, the focal length 7 equals 60 units, and the vector AG equals 91, hence the anti-parallel vector as here drawn to scale, in agreement with Fig. 19 of my said Case A.

If. instead of F, the lens to be used were. lens -E having a shorter focal length E E equal to E E equal e or 51 centimeters, and having its outer focal planeE located to meet the vector AG in G, then mirror N would have to be shifted to the lower or dotted position X so as to lie in the horizontal through G instead of in the horizontal through G. s

Shifting the eye mirror from X to X shortens the vector from the value AG to the value AG, without changing its inclination or the value of the basic angle r of the focuser, for r at G is exactly equal to r at G; the vector AH, therefore remains inclined as for lens F, but in view of equation 5. it shouldbe shorter, or only as long as indicated by AJ. The new focal length 6 and the new vector AG. by actual measurement onthe' original Fig. 19 of the said Case A. are respectively equal to 51 and 7 9 units. and these values inserted in equation 5 yield:

tance. J to j, that is equal to d. In other words, the pin J should be mounted on frame 12, so as to occupy position J for lens F". and so as to occupy the lower.

slightly offset position 7' for lens E.

The position Xor X of the. eye nnrror, and the position J or of pin J, can always and very easily be determined in this manner, provided the principal focal planes and the focal length of the lens to be used are, as here assumed, fully given and plotted; but. as a rule. the exact optical dimensions of the lens are unknown, and it is preferable to proceed by a methodical use of focusing adjustments, which should, of course. lead to the same definite results as if all fundamental dimensions of the lens to be used were known. 4

Any theoretically correct method of regulation should evidently place the eye mirror at X for lens F". and at X for lens E;

, and it should likewise place the pintle J on frame 12. in position J for lens F, and in position j for lens F).

I shall fully describe two theoretically correct methods ofregulation, to wit: first,

the slow, tedious, tentative method which I disclosed Aug. 11, 1900, in and as part of my said case A; secondly, the far preferable. novel. quick. easy. and positive method of regulation which I was not able to describe in presentable form before the filing date of the present application. These two methods of regulation, leading by different routes to the same final result, may therefore be identified and distinguished as (1) the tentative regulation of v1900: and (2) the positive regulation of 1918.

Tentative re 9 u-Za tion \I of 1900.

The 1900 method of regulation is here reproduced substantially as given in my said Case A, page 10, line 72, to page 11, line 14", but I am now able to present it in a form that is briefer, much clearer, and also slightly improved as to substance.

The focuser should be adjusted and regulatcd, to secure exact correspondence of focuser and camera indications, for at least three differently distant objectpoints, in a manner similar to that described page 5, lines 59 to 114, and Fig. 2 of my said Case A, for locating the scale Q. in Fig. 1 of said Case A. K Y

These three differently distant object points 0, 0, 0, when observed, must lie,

as shown in the present Fig. 1, in the horishould preferably be located one, 0 ata great, distance or infinity; the second, 0, very close; and the third, 0", between the other two, about twice as far off as the closest, so that the ray from it to point A will approximately hisect the angle formed by the rays oA and 0"A, coming from the other two points.

-T he observer first clamps the eye mirror tentativelv about where he believes it should be for the lens F that he is using, say in a probably incorrect position N, Fig. 1, and he then proceeds with the regulation proper, which comprises three different steps, to wit: first, regulation for the distant point '0'; second, regulation for the close point sible camera image of the said distant point "explained in the following step three:

0. Then, looking into mirror N, he temporarily clamps arm 51 to frame 12, in the angular position which produces a mended focuser image of the same said distant object point 0', as indicated for an object I point 0, in Fig. 8 of my said Case A.

Finally, with a scribing point, which is guided to run midway between the tempora-rily fixed inside wallsof slot R, he marks on frame 12, a line 40, such as seen in Fig. 7

Ste tw0.Selecting a close object point 0", Fig.4, the observer repeats the three operations of. step one on said close object point 0", to obtain on frame 12, asecond and less inclined line 50,which intersects line 40 in a point such as Vin Fig. 9.

Point V thus obtained might, in any case,

be used as indicating a sufliciently correct location for the intle J, because such location evidently -secures exact two-point correspondence between the focuser, and the camera, for the given-pointof, and'for the But 3-point eorre spohdence is obtainable, and it should espe' given close point 0''.

cially be secured because, in the present type of focuser, it simultaneously insures allpoint correspondence.

Hence it IS necessary ,to determine whether the position of V may'not be improved, as

Step tha'ee.Select1 n.g an intermediate object point 0", Fig.4, t e observer again repeats the three operations of step one on said intermediate object point 0", to obtain on frame 12, a third and intermediately in clined line which will surely pass through the same point V', Fig. 9, if the tentatively selected position N of the eye niirror really wasthe correct or N osition. k

If this third line, not shown, misses the said point V of fstep two the eye mirror must be shifted from its first selected and therefore incorrect position N, to a second, more correct, tentative position N, and the whole process must be repeated, beginning with step one, until the three lines marked on frame 12 intersect in one same point V, which will then be the correct position of pin J on frame 12, not only and evidently, for the three-object point 0', o", 0" which were used in regulating and adjusting the 'focuser;=but also, and in view of theprinciple embodied in Fig. 1 of my said Case A,

for any other arbitrarily selected object points to any number, and without limit.

Simpler steps one and two.- If the dis- .tant point 0 be relatively close, as assumed in describing step one above, every correcting displacement of the eye mirror N will yield an entirely new set of intersecting lines on frame 12. Y

If, however,'the distant point 0' is virtually situated at infinity, as it would be if the distance o'G were sayequal to about ten thousand times the focal length of the the first obtained line 40 really answers for all positions N, 1 Y, N, N of the eye mirror, and such first obtained line 40 may, therefore, be used as indicatin the place,

Fig. 3, where the guide-rail 39, should permanently be fastened to the frame 12 for the given lens F". 4

' not only avoidsrepetition of step one and the retracing of line 40, but, it also does away withthetracing of any sec-' 0nd line 50, Fig. 9, in observations on the point o for point 'V' is then found in close step two by simply sliding pin J along on its guide rail 39 until a" mended focuser image of c." has, been obtained.

Positive regulation of 1918.

By the tentative regulation of 1900, the adjustments were made first for the point oi, Fig. 4, at infinityfsecondly, for the point a", at close range; thirdly, and finally, for the point 0" This last,.however,-is in the nature of v a verification rather than in the nature of an adjustment, for it simply ,serves to verify the correctness of the initial and tentaat an intermediate distance.

tively made adjustment N orN of the eye l begins with the closest point 0', Fig. 4 as the first, and it makes such closest point as 'close as possible by placing it at G, in the outer principal focal plane F of the lens F to be used. l

Instead, therefore, of-focusing in the Fig. 4 order 0', 0", 0' of 1900, by my present improved and positive method I focus in the order'o", o, 0", and the object point 0" must be in the outer principal focal plane of thelens used, so that the corresponding camera extension F 1 as measured from the principal focusFg, Fig. 9, shall be infinite. v I

The focuser is therefore-adjusted and regulatedready for use with any one of dif ferent lenses, by means of three entirely independent and positively made focusing adend, at 56, to admit and firmly support a' ground glass scre'en57, whose inside or righthand face 15 the ground face.

The usual ground glass 15, Fig. 1, is removed in Fig. 6, so that the rays coming;

from right-hand infinity, may be admitted as indicated by the three heavy arrows, through the rear frame 12 of the camera, to be brought to a sharp focus on screen 57, by sliding the camera frame 10, 13, along on bench 55, while the observer is looking from the left, with a. properly adjusted magnifier, through screen 57. i

The real conjugate position of frame 12,

for screen 57, is, in such case, at right-hand infinity. Now, if frame 12, in the completely regulated camera of Fig. 1, could be moved all the way to infinity. it would lower arm 51, bringing'it gradually, and eventually, intothe horizontal or limiting position of Fig. 6. v .Thefocu'ser arm 51 should, therefore, occupy this exactly horizontal position of Fig. 6, whenever the'fcamera is focused, as

in said Fig. 6, on the outside principal focal plane F of lens F". being used.

This fixes the corresponding inclination of mirror M so that a ray TA, reflected on mirror M, at A, would proceed along R to meet the screen57 in a certain object point G. This point G radiatesi back: along the same path R, 61 and its identification is facilitated, for the observers eye at E, by its observed coincidence with some charac teristic point of a design which is marked on screen 57, where itwillsurely cover the probable location of G. r

Now, if the observer shifts to "the right, and looks horizontally into the-eyemirror at N, or at N. he will see, atA. or at A.-

the centrally reflected image of. the central sighting mark. of mirror M; and he will si multaneously see. at the same level as A, or A, the centrally reflected image of the said object point G. I

This centrallyirefiected virtual image of G, being invariably situated onthe horizontal through the eye mirror N, or X.

' may be raised or lowered, at will, by simply raising or lowering the said eye mirror; and it may thusbe brought to stand on a level with, but'as seen in Fig. 6, considerably to the left of its original object point G. In such leveled position it must. for an observing eye at the same level, apparently coincide with G, indicating that the eye mirror has been'set in its proper or N position for the given lens F The present adjustment number one may, therefore, be briefly described as follows The observer must (a) temporarily clamp the camera-bed 13 to the bench 55, as in Fig. 6, where he can see, on screen 57 the sharpest possible image of an object point at right hand infinity; (5) he then temporarily clamps arm 51 to bed 13 in the horizontal position of Fig. 6; (0) now, looking from the right hand side horizontally into the eye mirror, he notes that the centrally reflected object point image is that of a certain clearly identified object point G, on screen 57 ((1) he then lowers, or raises, the

eye mirror until the said centrally reflected eye mirror to rail 34, Fig. 1, in its thus determined proper posit-ion N, by tightening screw 37.

. Adjustment number t-'w0.Adjustment number two, shown as completed in Fig. 7, is substantially identical with the simpler step one described above, and it similarly determines the locus t0 of pin J -on frame 12. It is made by focusing on an object point situated at left-hand infinity, and it may briefly be simimarized in a series of distinctly indicated operations, as follows: (a) replace the ground glass 15, which was temporarily removed in carrying out the first-descrlbed adjustment "number one (b) temporarily clamp frame 12 tobed 13,

in focused relation on left infinity; ("c) raise ed focuser image of the object point at left infinity; (d) scribe line 40; (e) fasten guide rail 39 to frame 12, directly over line 40 as indicated in Fig. 3; (f) mount piirJ' on its rail 39 and inoperative engagement with slot. R, but leave the clamp screw 38' loose.

Adjustment number three.Adjustment number three is identical with the abovedescribed simplerstep two. Itmay.therefore, briefly be summarized in a few distinctly indicated operations as follows: (a) temporarily clamp bed 13 of the camera to the bench 55 about where shown in Fig. 9; (b) temporarily clamp frame 12 to bed 13 in properly focused relation on screen 57: (0) shift pin J along on its guide rail 39 to mend the focuser image of the object point V which is the same point of screen '57 that served as point G in adjustment number one; ((1) and finally, tighten the clamp screw 38".

The focuser, being what I have called in my said Case Ae a theoretically exact focuser, is now accurately adjusted and regwiththe given lens F".

- Improved Fig.9.. to 15 mou n -t for pin J'.-

Themark 40, Figs. 3, 7 and9, used to locate rail 39 with its two permanent fasteners 39 and 39", is hardly more than a workshop expedient. It answers well enough for any one given lens provided no error is made in driving the permanent fasteners 39' and 39". Where any such errorwas made, its correction is apt to present greatdifii'culties, because the old set of holes, even if refilled, may interfere seriously with the proper location of. any-desirable new set. Moreover, the mere necessity of driving per,- manent fasteners exactly in certain indicated positions is, iii-itself, objectionable because it always requires care; and skill; also because, in spite of any care and skill that may in such case be exercised, the grain o1 thewood will often lead andforce a. fastener to one side of its intended position.

0 A solution tha'tois free from all such object-ions and that furthermore has the ad vantage of being simple aswell as completely mechanical and eflicient, is shown V of solder may be used to insure 1t against Fi lQ to 15. A

' ere the rail 39 of Fig. 3 is replaced by a bar 139 having. alongitudinal undercut slideway or groove llO, also a longitudinal slot 141, Figs. 13 and 15, which is traversed by a clamp plate 142, whose two ends are fastened to frame 12 by two clamp screws 113 and 14-1. v

The undercut groove 140 admits nuts such as 116, 117, Figs. 12. 13 and 15, which respectively receive bolts 116', 147', thatmay be fixed ,at any desired points of the slideway 110 by simply screwing them through their nut until they press firmly against the bottom of groove 110, as best shown in Fig. 15.

\Vhen the two clamp screws, 143, 1 1-1 of clamp plate 142 are loosened sufficiently, bar

139 may he slid around, raised, lowered, shifted laterally or longitudinally, and generally moved so that it may be brought into any arbitrarily desired position with relation to frame 12; and it may then be firmly fixed in such desired relative position, by ret-ightening the said two clamp screws 113. 1 1-1.

The desired relative position of bar 139 to frame 12 is determined in the course .of

the above described adjustment number two, in substantially the same manner as illustrated in Fig. 7, for determining the position of line =10, which is nolonger needed.

The whole operation is rendered positive, and quasi-automatic, by, temporarily connect-ing bar 139, as shown in Fig. 14, with likewise be'insured a Having loosened the two screws 113,11H,

and having temporarily clamped frame 12 to bed 13 in focus on left infinity, as in Fig. 7, the obverver raises arm 51, together with its bar 139,-until he has obtaineda mended focuser image of the same object point at left infinity; and the bar 139, is then firmly clamped to frame 12 in its thus self-deter mined proper position on frame 12, by tightening the two clamp screws 143, 14-1. Its exact'distance from D is immaterial.

One of the said two bolts 1&6, 117 must now be removed, and the remaining one, say 146 is kept to serve in place of the pin J of Figs. 1 and 3..

This bolt 146' is therefore properly located on its bar 139 by means of the same adjustment number three which was de scribed above for locating pin J on the screwing it through its nut 1'46 against the bottom of the undercut. groove 140. A- drop any 'subsequent loosening or displacement on its bar-139, r

If the camera frame 12 is metallic or metal-covered; the bar 139 may easily and inst accidental loosening or displacement y the use of properly distributed drops of solder,

Angle delta (A) in Fig. 1.

and particularly in the equation annexedto and forming part of its Fig. 23), lays stress on the present angle 1' at G as being the important. angle of the focuser, andI have,

therefore, so far called it the basic angle.

On the other hand, my later radial cam Cases Y, -Ae, 'At, Au, lay-stress on a certain other angle delta (A) as being the basic angle of the focuser. As a matter of fact, any given focuser of the radial cam type, either optical or wholly mechanical, contains more or less concealedin itsstructural embodiment ('1) an angle that is identical with the said angler atG of my saitLCase A; and (2) another angle that is identical with the said basic angle delta (A). g

It is, therefore, desirable to show where this angle delta (A) occurs inthe optical focuser of Fig. 1. Referring to Figs. 6 and 7, it is plain that the radial slot in arm 51, and the incident ray R, determlne an obtuse angle which may be indicated by an imaginaryarc delta ibHSlG' angle 1" at G.

' at its'lower end produced. it meets the produced horizontal axis 'ofslot R, to form the angle delta (A).

That the angle delta (A), equal to 7* at- G in Fig. 6, must inany other position of arm 51, remain invariably equal to r at G. is dependent upon the fact that arm 51 and the incident ray R, are 'bound to rotate in the same direction and at the same rate. This may be proved as follows:

If the mirror M is turned counter-clockwise from its Fig. 6 position, through any given angle of 0 degrees. it is evident that the-incidental 'ray R will likewise be rotated counter-clockwise. but through an angle of twice (1 degrees. It is. furthermore. evident that this same counter-clockwise rotation of (1 degrees in mirror M. must be produced by a counter-clockwise rotation of twice a degrees imparted to arm 51. That is to say, any angular displacement of 2a degrees imparted to arm 51 and its slot R. is likewise and simultaneously imparted to the incidental ray R. V

The relative inclination of the incidental ray R. to the radial slot R. is therefore invariably equal'to the basic angle 1' at G. not only when arm 51 is horizontal as in Fig. 6. but also-when it has been turned up into any other position.

Tl1us.'in Fig. '7. where the radial slot R- of Fig. 6 has been turned up or counterclockwisethrough the-angle eta (a), the mirror M has been turned counter-clockwise through one-half ofangleeta (a), and the incident ray R has been turned down or counter-clockwise from its Fig. 6 position through twice one-half eta, 'or through eta, here represented by the equal angle eta prime (77'). The relativeinclination delta (A). of'R' to R...in Fig. 7, is therefore exactly the same as it was in Fig. 6.

Now. let the inclination of mirror M with reference to mirror N in Fig. 6 be represented by mu (a) so'that said mirror'M must 'be rotated counter-clockwise, through an angle equal toangle mu '(u), in order to assume the parallel or zero-inclined position of Fig. 7.

It is then obvious that angle mu (a) must be equal to one-half angle eta (n),'ormore clearly, that" But angle eta ('11) of Fig. 7, is evidently the angular supplement of angle delta (A). so that. in view of'equation 3. the value of angle delta must be equal totwo right. an gles minus twice angle mu; or in symbols, using Q as before. for the quadrant or one right angle,

AIQQ Q ue-la (a That is to say. the relative inclination mu (a) of the mirrors in Fig. 6, determined automatically while making adjustment nunr her one," predetermines the basic angle delta (A) of the focuser.

This important principle establishes the theoretical identity that exists between the optical radial cam focusers of my said Case A. and the mechanical radial cam focusers of my said Case Au.

The Fig s. 16 10 531 camera. I s

As the incidental ray R of Figs. 6. 7. and 9 does rotate in constant angular relation delta (A) with the radial slot R. the mirror M of these figures may be replaced. as in Figs. 16. 17. and 19. by a plain alidadc or sighting arm 300 which is pivoted at A, and which is mechanically connected to the whence radial arm 300. or R. by means of a rigid his eye to E. in alinement with D'R, as in Fig. 1 of my said Case A. The mirror'retained at N simply serves as a peep sight which cooperates with the image A of A as a bead sight. 7

The regulation of the Fig. 16 camera is identically the same in principle as that of the Fig. 1 camera, and the three different phases of such regulation may, therefore, be illustrated as in Figs. 16, 17. andlt). corresponding respectively With Figs. 6, 7 and 9.

The Figs. to 27 camera- The camera of Fig. 16 may be calledau two-sightfocuser to distinguish it from the double-sight focuser of Fig. 1. as well as from the single-sight. focuser of my said Case At.

An extremely simple form of two-sight 

